Power tool component position sensing

Patent metadata

Field	Value
Publication number	US-11465264-B2
Application number	US-201916708582-A
Country	US
Kind code	B2
Filing date	Dec 10, 2019
Priority date	Dec 11, 2018
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

Position sensing related to a component within a power tool. The component within the power tool is, for example, a hammer of an impact mechanism and can include one or more sensible features that allow a controller of the power tool to precisely determine the position, speed, and acceleration of the component. One or more sensors can be used to determine the rotational position of the hammer and the axial position of the hammer. The rotational position of the hammer can then be used to calculate, for example, rotational speed and acceleration of the hammer. With precise determinations of the rotational and axial position of the hammer, the controller of the power tool is able to precisely time the impact between the hammer and the anvil to optimize the impact between the hammer and the anvil (e.g., to maximize energy transfer between the hammer and the anvil).

First claim

What is claimed is:

1. A power tool comprising:
a motor;
an impact mechanism coupled to the motor, the impact mechanism including:
a hammer driven by the motor, the hammer including a first sensible feature and a second sensible feature, wherein the first sensible feature is a cutout portion of the hammer and the second sensible feature is a non-cutout portion of the hammer, and
an anvil configured to receive an impact from the hammer,

an impact case housing the anvil and the hammer;
a sensor configured to generate an output signal indicative of a rotational characteristic of the hammer by sensing the first sensible feature of the hammer and the second sensible feature of the hammer; and
a processing unit connected to the sensor and to the motor, the processing unit configured to control the motor based on the output signal from the sensor.

2. The power tool of claim 1 , wherein the hammer includes a third sensible feature.

3. A power tool comprising:
a motor;
an impact mechanism coupled to the motor, the impact mechanism including:
a hammer driven by the motor, the hammer including a first sensible feature, a second sensible feature, and a third sensible feature,
wherein the first sensible feature, the second sensible feature, and the third sensible feature are located on a projection of the hammer,
wherein the hammer includes a plurality of projections, and

an anvil configured to receive an impact from the hammer,

an impact case housing the anvil and the hammer;
a sensor configured to generate an output signal indicative of a rotational characteristic of the hammer by sensing the first sensible feature of the hammer and the second sensible feature of the hammer; and
a processing unit connected to the sensor and to the motor, the processing unit configured to control the motor based on the output signal from the sensor.

4. The power tool of claim 3 , wherein each of the first sensible feature, the second sensible feature, and the third sensible feature is varied in size for each of the plurality of projections based on a circumferential location of each projection of the hammer.

5. The power tool of claim 3 , wherein:
the first sensible feature is a flat circumferential surface of each of the plurality of projections;
the second sensible feature corresponds to a height of each of the plurality of projections; and
the third sensible feature corresponds to a ramp between adjacent projections.

6. The power tool of claim 3 , wherein:
the rotational characteristic of the hammer is a rotational position of the hammer; and
the processing unit is configured to determine the rotational position of the hammer based on the output signal from the sensor.

7. The power tool of claim 6 , wherein the processing unit is configured to determine a rotational speed of the hammer based on the output signal from the sensor.

8. A method of controlling a motor of a power tool, the power tool including an impact mechanism, the impact mechanism including a hammer and an anvil, the method comprising:
sensing a first sensible feature of the hammer using a sensor;
generating an output signal from the sensor, the output signal having a first value related to the first sensible feature of the hammer;
sensing a second sensible feature of the hammer using the sensor;
generating the output signal from the sensor, the output signal having a second value related to the second sensible feature of the hammer,
wherein the first sensible feature is a cutout portion of the hammer and the second sensible feature is a non-cutout portion of the hammer;

receiving the output signal at a processing unit; and
controlling the motor of the power tool based on the output signal having the first value related to the first sensible feature of the hammer and the second value related to the second sensible feature of the hammer.

9. The method of claim 8 , further comprising:
sensing a third sensible feature of the hammer using the sensor;
generating the output signal from the sensor, the output signal having a third value related to the third sensible feature of the hammer.

10. The method of claim 9 , further comprising:
determining the rotational position of the hammer based on the output signal from the sensor.

11. The method of claim 10 , further comprising:
determining a rotational speed of the hammer based on the output signal from the sensor.

12. A method of controlling a motor of a power tool, the power tool including an impact mechanism, the impact mechanism including a hammer and an anvil, the method comprising:
sensing a first sensible feature of the hammer using a sensor;
generating an output signal from the sensor, the output signal having a first value related to the first sensible feature of the hammer;
sensing a second sensible feature of the hammer using the sensor;
generating the output signal from the sensor, the output signal having a second value related to the second sensible feature of the hammer;
sensing a third sensible feature of the hammer using the sensor;
generating the output signal from the sensor, the output signal having a third value related to the third sensible feature of the hammer,
wherein the first sensible feature, the second sensible feature, and the third sensible feature are located on a projection of the hammer,
wherein the hammer includes a plurality of projections,

receiving the output signal at a processing unit; and
controlling the motor of the power tool based on the output signal having the first value related to the first sensible feature of the hammer and the second value related to the second sensible feature of the hammer.

13. The method of claim 12 , wherein each of the first sensible feature, the second sensible feature, and the third sensible feature is varied in size for each of the plurality of projections based on a circumferential location of the of each projection on the hammer.

14. The method of claim 12 , wherein:
the first sensible feature is a flat circumferential surface of each of the plurality of projections;
the second sensible feature corresponds to a height of each of the plurality of projections; and
the third sensible feature corresponds to a ramp between adjacent projections.

15. A hammer of an impact mechanism for a power tool, the hammer comprising:
a projection including a first sensible feature, a second sensible feature, and a third sensible feature.

16. The hammer of claim 15 , wherein:
the hammer includes a plurality of projections, and
each projection includes the first sensible feature, the second sensible feature, and the third sensible feature.

17. The hammer of claim 16 , wherein each of the first sensible feature, the second sensible feature, and the third sensible feature is varied in size for each of the plurality of projections based on a circumferential location of the of each projection on the hammer.

18. The hammer of claim 17 , wherein:
the first sensible feature is a flat circumferential surface of each of the plurality of projections;
the second sensible feature corresponds to a height of each of the plurality of projections; and
the third sensible feature corresponds to a ramp between adjacent projections.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Schneider Jacob P
• Dey Iv John S
• Obermann Timothy R

Classifications

• B25F5/00 Primary

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• B25B21/023

  for imparting an axial impact, e.g. for self-tapping screws · CPC title

• B25B23/1475 Primary

  for impact wrenches or screwdrivers · CPC title

• B25D11/068

  in which the tool bit or anvil is hit by a rotary impulse member · CPC title

• B25B21/026

  Impact clutches · CPC title